Surface treating machine



Nov. 17, 1942. J. DELNOSTRO 2,302,424

SURFACE TREATING MACHINE Filed Nov. 24, 1941 3% why? Patented Nov. 17, 1942 UNITED STATES PATENT OFFICE 1 SURFACE TREATING MACHINE Joseph Delnostro, Cleveland, Ohio Application November 24, 1941, Serial No. 420,287

8 Claims.

The present invention relates to surfacing machines, and more particularly to power driven devices or tools adapted to be manipulated over a surface for grinding, polishing, buffing or otherwise treating the same.

In machines or tools of this type it is customary to employ an electric motor to drive a member which vibrates a pad, sheet or other element bearing the abrasive, polishing or other medium for effecting the desired surface treatment, The operator moves the machine over the surface which is to be treated, and the principal object of this invention is to improve machines of this type in respect of their ability to accomplish the desired surfacetreatment, durability, cost of manufacture and maintenance, and general serviceability.

Incidental objects are concerned with rendering the device easier to operate than the best known prior art machines and less wearing on the operator.

The machine which is the subject of the present invention has been thoroughly tested in practical use and accordingly the invention Will be described in a preferred form of embodiment which has been found to be entirely satisfactory in actual use. The invention comprises several features of superiority over the known art and is capable of modification and deviation from the preferred embodiment which is illustrated on the accompanying drawing and will be described in this specification. The invention is not limited to the conjoint use of all the improved features, inasmuch as they can be variously embodied and employed alone or in other combinations. Accordingly, the claims have been drafted to cover the features of improvement whether used separately or in various combinations with one another.

In the accompanying drawing:

Figure l is a side elevational view of a machine embodying the invention, with certain portions of the lower assembly broken away to show the interior parts;

Fig, 2 is a bottom plan view with certain parts similarly broken away; and

Fig. 3 is a detail sectional view taken through one of the side plates, showing particularly the air outlet opening and deflector.

The machine is particularly, although not exclusively, intended for use in grinding a metallic sheet or the like, which may be sandpaper, emery cloth or any other kind of analogous material, mounted on a back plate or support which is preferably relatively rigidly connected to an electric motor casing or base. The motor drives an unbalanced element which is not directly connected to the sheet or its backing plate, but which induces vibration into the machine as a whole. so that the backing plate and the sheet which it mounts are vibrated over the surface which is to be treated. It will be evident that a machine thus operating cannot be stalled no matter how hard it is pressed against a stationary surface, and in this respect the machine is superior to those employing a direct connection between the motor and the vibratory plate or sheet.

In the illustrated embodiment the casing of a high speed electric motor is designated I. At the upper portion of the casing a pistol grip handle 2 having a switch button 3 in a circuit including a cord 4 is rigidly mounted. A cooperating handle 5 extends diametrically from the handle 2 and is conveniently hinged at about its mid-portion 6 so that its terminal end I may be folded back over the motor casing when the device is not in use. The end I conveniently takes the form of a relatively soft rubber body, onto which the operator can bear with more or less pressure when the device is being used.

The motor casing terminates at its bottom in an outwardly directed flange 8 to which is secured, by bolts 9 or otherwise, the upper edges of a back plate or support ID of special shape. The member ID is of general box-like form, open at its sides and top and preferably rectangular in plan. At each of its ends, about midway between the upper runs which receive the bolts 9 and the body portion l I closing the bottom of the structure, the plate is inwardly recessed, as shown at l2, for a purpose hereinafter to be explained. Below one recess I2, which may be designated the front recess, the end wall of the plate projects forwardly to form with the body portion II a relatively sharp edge l3 which extends well beyond the adjacent upper portions of the device.

A resilient pad M, of felt, soft rubber or the like, underlies and is secured to the under face of the body portion H of the plate, and the sheet l5, or a plurality of such sheets, bearing abrasive, polishing or other material, are disposed along the pad and into and beyond the recesses l2, in which the margin of each sheet is held by a clamping device l6. As shown, this clamping device comprises two U-shaped elements of comparatively soft rubber stock yieldably urged together by helical side springs II. In this way a sheet l5 or a stack of such sheets may be clamped in operative position on the supporting or back plate, and it will be obvious that if the machine as a whole is vibrated the operative face of the lowermost sheet will be likewise vibrated.

Vibration isaccomplished by mounting on the end portion l8 of the motor shaft, which projects partially into the space between the motor base 8 and the body portion ll of the sheet support, an unbalanced rotor l9, This rotor is made fast on the shaft in any conventional way and comprises, in the preferred embodiment of the invention, a portion 20 which extends farther from the hub of the rotor than does a diametrically opposite portion 2|. Rotated at a high rate of speed this unbalanced rotor will cause the entire machine or tool to vibrate. The operative face of the lowermost sheet I 5 is thus given a generally gyratory circular motion of small radius which exercises a most eflicient grinding action on any surfaces against which the device may be held. Of course polishing, buffing and other kinds of treatment will be accomplished, depending on the character of the sheet that is used.

The open sides of the space between the motor base and the sheet support are normally kept closed by a pair of side plates 22. Each of these has an upper inturned flange slotted at 23 to be caught by the bolts or the like 9 and thus be held in depending position to close the space which contains the rotor. The space is not completely closed, inasmuch as air inlet openings are provided as at 24 in the upper zone of each plate 22, and the bottom margin of each plate is spaced slightly from the adjacent face of the body portion H of the support, as shown at 25. These openings respectively admit and discharge air induced into the space by a blade 26 conveniently formed on the rotor, which thus is made to act like a fan or impeller. Air entering the openings 24 is discharged through the space 25, whence it is deflected by the outwardly bent lower margin of each plate 22, best shown in Fig. 3, directly over the edge of the sheet l5 down onto the surface which is being treated. Thus particles of abrasive matter, dust and the like ground from the surface will be blown aside automatically and regularly as the surface treatment operation progresses.

The provision of the relatively sharp leading edge I3 at the base of the machine enables the operator to perform a superior job of feather edging and gives the machine access to difficu corners of the surface to be treated.

Interposition of the resilient padl4 between the stiff backing plate and the sheet cushions the vibration of the sheet and will be selected with a degree of softness appropriate to the particular kind of work to be performed.

It is obvious that operation of the machine involves no wear of the parts except of course the bottom-most sheet I 5. When such a sheet is worn out it is simply torn from the machine and the operation proceeds with the next sheet of the stack. Replacement of sheets is readily accomplished bysimply loosening the clamp l6 against the tension of the springs l'l. Since there is no direct connection between the vibratory rotor and any other part of the machine, except the shaft l8 on which the rotor is fast, there is no wear anywhere in the machine except at the shaft bearings. Hence no lubrication is required anywhere except at such bearings, and if desired these may be made of the self-lubricating, or permanently lubricated type.

It is believed that from the foregoing it will be evident to those skilled in the art that I have provided and herein disclosed a surface treating machine capable of achieving all the objects and of providing all the advantages stated hereinabove. Indeed, further advantages will be recognized by those skilled in the art. For example, while the handle Ii has been explained as being hinged at 8 so that the terminal end 1 may be folded back over the motor casing when the device is not in use, it will be found that the handle can be advantageously disposed in folded back position under certain conditions of use also, as for example in cases where it is desirable to apply pressure directly over the motor casing, or where a surface in some otherwise inaccessible corner is to be treated.

I claim:

1. A surfacing machine comprising a motor having a casing and provided with a rotary shaft extending beyond the casing, an unbalanced rotor fast on the extended portion of the shaft for vibrating the casing when the motor is operated, a support connected to the casing and extending across the axis of the shaft beyond th rotor and spaced therefrom, a surface-treating sheet disposed across the outer face of the support, and walls partially enclosing the space between the casing and support and providing inlet and outlet openings cooperating with the rotor to induce an air current into the space and out therefrom on to the portions of a surface being treated which are adjacent to the edges of the surfacetreating sheet.

2. In a surfacing machine of the type in which power means vibrates a support for a surfacetreating sheet, the combination of a support hav ing a generally rectangular body area terminating in a leading edge extending out beyond all adjacent parts of the machine, a portion of the support along said edge being curved back on itself above said body area and connected to the casing, the support at said leading edge being relatively thin and having a sheet of surfacetreating material disposed thereover adapted for use in feather edging.

3. A surfacing machine comprising a motor having a casing and provided with a rotary shaft extending beyond the casing, a support carried by the casing and having a body portion spaced therefrom adapted to mount a sheet of surfacetreating material, means driven by the shaft for vibrating the support, wall elements partially closing the space between the casing and the support, and fan means carried by the shaft for inducing a current of air into said space and blowing the same out therefrom over the edges of the body of the support.

4. A surfacing machine comprising a motor having a casing and provided with a rotary shaft extending beyond the casing, an unbalanced rotor fast on the extended portion of the shaft for'vibrating the casing when the motor i operated, a

support connected to the casing and extending across the axis of the shaft beyond the rotor and spaced therefrom, a surface-treating sheet disposed across the outer face of-the support, walls partially enclosing the space between the casing and support and providing inlet and outlet openings for said space, and a blade extending from the rotor for inducing an air current into the space and out therefrom .on to the portions of the surface being treated which are adjacent to the edges of the surface-treating sheet.

5. A surfacing machine comprising a motor mounted on a base, a rigid shaft for the motor having a bearing and a free, unsupported end portion projecting from the bearing, an unbalanced rotor fast on said end portion for vibrating the base when the. motor is operated, a rigid backing member carried by the base for vibration therewith, and a surface-treating element carried by the backing member.

6. A surfacing machine comprising a motor having a casing, a rigid shaft for the motor having a bearing carried by the casing and a free,

unsupported end portion projecting from the bearing and extending outwardly beyond the casing and said bearing, an unbalanced rotor fast on said free end portion for vibrating the casing when the motor is operated, a rigid backing member carried by the casing for vibration therewith beyond the free end portion of the shaft and unconnected therewith so as to be spaced from the terminal of said free end portion, an unbalanced rotor fast on said free end portion for vibrating the casing and backing member when the motor is operated, said rotor being spaced inwardly from the flat central portion of the backing member and-being unconnected therewith, and a. surface-treating element carried by said fiat central portion of the backing member.

8. A surfacing machine comprising a motor having a casing provided with a laterally flanged base, a rigid shaft for the motor having a bearing carried by the casing and a free, unsupported end portion projecting from the bearing and extending outwardly beyond the casing and said bearing, a generally U-shaped rigid backing member having laterally directed flanges at its ends rigidly connected to the flanged base of the motor casing and including a fiat central portion transverse to the axis of the shaft, spaced outwardly beyond the free end portion "f the shaft and-unconnected therewith so as .t; be spaced from the" terminal of said free end portion, an unbalanced rotor fast onsaid free end :portion for vibrating the casing and backing member member.

'JOSEPH DELNOSTRO. 

